1. Technical Field
The present invention pertains to thermal coatings in general, and to coatings for minimizing thermal gradients along the surface of an article in particular.
2. Background Information
It is often advantageous to minimize an article's exposure to thermal energy. In sufficient quantities, thermal energy can cause thermal expansion of an article and in some cases undesirable thermal stress within the article. Thermal stress, in turn, can manifest as stress cracks, reduced ductility, or distortion of the article. This is especially true in instances where the thermal energy is concentrated in a particular region of the article, resulting in a steep thermal gradient within the article.
Insulative coatings may be bonded to the exterior surface of an article to minimize the article's absorption of thermal energy. Typically, the coating has a thermal conductivity value lower than that of the article (or a higher thermal resistance value) and/or a high degree of thermal reflectivity. In many cases, an insulative coating alone is sufficient to prevent or minimize thermal stress within the article. In instances where the thermal energy is concentrated, however, coatings or other insulative means may not be sufficient to prevent the growth of a thermal gradient capable of creating thermal stress within the article.